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force field "radial distance" has no effect
Closed, ResolvedPublic

Description

System Information
ubuntu 14.04, 630GT

Blender Version
Broken: 2.73

Short description of error

tube or cone radial -> use_maximum has no effect

setup

alt+a

the wind effect should be limited to the tube

Exact steps for others to reproduce the error

blend

download the blend and hit alt+a

Event Timeline

Ronny G (nutel) updated the task description. (Show Details)
Ronny G (nutel) raised the priority of this task from to Needs Triage by Developer.
Ronny G (nutel) added a project: BF Blender.
Ronny G (nutel) set Type to Bug.
Ronny G (nutel) added a subscriber: Ronny G (nutel).
Bastien Montagne (mont29) claimed this task.

Maximum distance works perfectly, as you can see by putting your force field away enough from your particles, it won't affect them at all.

But once your particles have gained energy from a force, they won't loose it at all in Blender's ideal world, so they will just keep going on forever. Unless you add them some damping, of course… ;)

Anyway, thanks for the report, but no bug at all here.

Ronny G (nutel) added a comment.EditedFeb 13 2015, 5:39 PM

it doesnt work here mont29

there is no force except the field and the force should be limited to the tube?

can you show me a screenshot or video?

edit:

with shape set to "point" it works but not with "plane"!

Nutel is probably talking about radial or angular maximum distance for Tube or Cone, not maximum distance for z axis.

I think that is a known limitation.
This kind of fall-off shape only works for Point force field and not for Plane Force Field.

mont29, I can confirm the issue. Only the +/- Z maximum is working, not the radial maximum in the tube falloff.

Note: This bug was already raised years ago at Blender conference during my smoke simulation masterclass.

Ok, my bad, closed that one too quickly.

Still, from a quick look to the code, I think there is no bug here, 'plane' shape simply cannot work with radial imho. Do not know that code well, though, so assigning to Lukas to get authorized opinion here. :)

Bastien Montagne (mont29) triaged this task as Normal priority.Feb 13 2015, 9:31 PM

Effectors are a mystery.

They have 2 different vectors to determine "distance":

  1. from the center to the particle
  2. from the center plane, orthogonal to the direction, to the particle

The radial distance should be determined by subtracting the normal component of the 1st vector - but the code actually uses the 2nd version instead, which has no radial component in the first place ...

I could try to fix this, but at the expense of breaking every existing setup (as usual...). *sigh*

Don't bother breaking things - there was another user at a Blender conference (I guess it was 2011) who also wanted this fixed.